1. Field of the Invention
The present invention is directed to fire barrier assemblies for apertures through which one or more electrical cables may pass and more specifically, to a novel construction of the frame and sealing elements for achieving the fire barrier.
2. Prior Art
The U.S. Pat. No., to Williams, 1,851,940, discloses a closure for conduits and the like having electrical cables passing therethrough wherein a septum or plug comprised of one or more pieces of resilient material having cutout portions for receiving the cables, is inserted into the conduit in close fitting relation about the cables. A pair of end plates on opposite sides of the septum or plug are then bolted together and upon being drawn together will force the resilient material into close intimate engagement with the conduit wall and the external surface of the cables.
The U.S. Pat. No., to Brattberg, 2,732,226, is directed to a pressure-tight packing assembly for conductors passing through a wall. The pressure-tight packing assembly consists of a short, rectangular tube which is filled in part with elastic blocks of varying sizes. Adjacent blocks may be provided with comlimentary grooves which will define a cylindrical passage for a specific size electrical condutor and some blocks are provided without grooves to merely act as fillers. After the blocks and cables are all assembled in the desired relationship, a final pressure sealing may be obtained between the conductors, the elastic blocks and the tube by compressing the blocks in a direction perpendicular to the cables by means of a common plate. Suitable arrangements are then provided to fill the gap left between the opposite side of the plate and the tube.
The U.S. Pat. No., to Anderberg, 3,976,825, is directed to a lead through for electrical cables which will be fire proof, gas proof and liquid proof at a predetermined temperature. The cables extend through an opening in a ceiling, floor or wall and a pair of complimentary guide strips, each of which is provided with a semi-cylindrical groove, surround each cable. Interfitting filling members are also provided to completely fill the opening. There is no compression applied to the filling members, guide strips or cables so that each of these elements may readily be withdrawn from the opening in order to change the configuration and add or substract cables passing therethrough. The guide strips and filling members are composed of a material having a high coefficient of cubic expansion whereby in the event of fire, the guide means and filling members will expand to form a tight seal within the frame and against the cables. One end of the assembly may be coated with a material to seal the spaces between the guide strips and the cables in a gas tight and liquid proof manner.
The U.S. Pat. No., to Bradley et al, 4,061,344, is directed to a fitting for penetration through fire rated barriers to provide for the passage of pipes, cables, or conduits. According to one embodiment of this patent, a plurality of layers or plates of intumescent material are provided in alternating relationship with one or more layers or plates of an elastomeric sealing material. A pair of rigid compression plates are provided on opposite sides of the assembly and are adjustably secured together by means of bolts extending through the assembly. One or more apertures may be provided through the plurality of layers or plates for the passage of a cable or the like. The rigid compression plates may be coated with an intumescent material and upon drawing the rigid compression plates together, the elastomeric plates will be expanded to closely grip the walls of the opening and the cables passing therethrough. The elastomeric material provides a gas and liquid seal at normal temperatures and upon being exposed to elevated temperatures, the intumescent material will expand to compensate for the destruction or shrinking of the elastomeric material and the insulation surrounding an electrical cable to maintain a tight seal between the opening and the conductor of the electrical cable. In another embodiment according to this patent, a single heterogeneous member comprising both the sealing material and the intumescent material is disposed between the two compression plates.